1. Field of the Invention
The present invention relates to an electromagnetic field intensity calculating method, an electromagnetic field intensity calculation apparatus, and a computer readable medium storing a control program, and more specifically to an effective technique applied to an electromagnetic wave analysis technique etc. for calculating the intensity of the electromagnetic field radiated from an electric circuit device such as electronic equipment, a circuit board, etc. on the basis of a moment method.
2. Description of the Related Art
For example, it is known that the moment method disclosed by the patent documents 1, 2, 3, etc. is used as a method for simulating and analyzing an electromagnetic wave radiated from electronic equipment. The moment method includes the steps of: dividing the conductor configuring the electronic equipment into planar elements called patches; calculating the electric current flowing through an adjacent element; and calculating the distribution of the electric field and the magnetic field generated on the basis of the current. The moment method is also referred to as a boundary element method.
In the electromagnetic field intensity calculation apparatus which calculates the intensity of the electric field and the magnetic field radiated from electronic equipment etc. on the basis of the moment method, it is important to realize high-accuracy and high-speed simulation to appropriately dividing and modeling a flat conductor pattern of a power supply layer, a ground layer, etc. of a printed circuit board of the electronic equipment to be analyzed.
In generating a model for an electromagnetic wave analysis, the arrangement/wiring data of a circuit element on the printed circuit board can be generated with ease relatively by fetching the CAD data from a computer-aided design (CAD) apparatus for designing a printed circuit board. However, it is necessary to first fetch the pattern form data of the flat conductor pattern of the power supply layer and the ground layer from the CAD, and then divide it into a mesh model appropriate for the moment method. Accordingly, a need still exists in the art to provide a method for correctly and quickly generating the mesh model.
Conventionally, as disclosed by the patent document 2, the form of the flat conductor pattern of a power supply layer, a ground layer, etc. obtained from the CAD data in the circuit board designing step is divided into a mesh model containing squares and triangles in a mixed manner.
Furthermore, where a plurality of flat conductor pattern layers exist in, for example, a multilayer wiring structure, it is necessary to select each flat conductor pattern for each layer, and input a division number each time for each layer, thereby dividing a mesh.
Although the above-mentioned conventional technique has the function of automatically dividing the flat conductor pattern of the power supply layer and the ground layer obtained from the CAD data into mesh form, the flat conductor pattern is divided as is into mesh form, and therefore squares and triangles are mixed in an obtained mesh pattern, which is not appropriate for the moment method.
That is, in the triangular mesh pattern shown in FIG. 1A, the electric current passing from each vertex to the opposite side is calculated. In the square mesh pattern shown in FIG. 1B, the electric current passing in the direction of the opposite side is calculated.
Therefore, for example, in a mesh pattern formed by a plurality of triangles and a mesh pattern formed by triangles and squares in a mixed manner as shown in FIG. 1C, the current passes unevenly, and delayed propagation occurs, thereby causing the degradation in precision of analysis.
On the other hand, in the case of a mesh pattern formed by a combination of squares as shown in FIG. 1D, the current smoothly passes, and therefore there is no delayed propagation etc. and high precision of analysis can be expected.
Therefore, as described above, in the conventional technique of dividing a flat conductor pattern into mesh form, it is necessary to simplify the form of the flat conductor pattern in advance by an upper CAD apparatus to configure the is mesh pattern by squares only in order to improve the precision of analysis. However, in this case, it is necessary in the step of the CAD apparatus to separately regenerate the CAD data for an electromagnetic wave analysis in addition to the original CAD data, thereby causing another problem of increasing the number of steps required for the entire designing steps.
When the power supply layer and the ground layer are formed by a plurality of layers, mesh data is generated for each layer as described above. Therefore, a boundary mismatch may occur between the layers as shown in FIG. 2.
In the electromagnetic wave analysis of a printed circuit board etc. of multilayer structure, a simulation is performed with the electromagnetic interaction between the layers taken into account. Therefore, the boundary mismatch of mesh data between the layers can be a factor of the degradation of precision of analysis.
Patent Document 1: Japanese Published Patent Application No. H5-95931
Patent Document 2: Japanese Published Patent Application No. H9-5375
Patent Document 3: Japanese Published Patent Application No.